Finned hollow article



J-COSPEN FINNED HOLLOW ARTICLE May 4, 1965 3,181,607

Original Filed June 15, 1959 2 Sheets-Sheet 1 6r w wwvi ATTUWNEYS J.COSPEN FINNED HOLLOW ARTICLE May 4, 1965 II 2 Sheets-Sheet 2 OriginalFiled June 15, 1959 6 Jul.

m m mm m m u I T INVENTOR. JEANCOSPEN ATTOR v i S United States Patent()fiice 3,181,607 Patented May 4, 1965 3,181,607 FINNEI) HOLLOW ARTICLEJean Cospen, Cachan, France, assignor to 01in Mathieson ChemicalCorporation, East Alton, 111., a corporation of Virginia Originalapplication June 15, 1959, Ser. No. 820,244, now Patent No. 3,121,940,dated Feb. 25, 1964. Divided and this application Aug. 30, 1963, Ser.No. 318,462

2 Claims. (Cl. 165-170) This application is a division of applicationSerial No. 820,244, filed June 15, 1959, now United States Patent No.3,121,940, granted February 25, 1964.

This invention relates to hollow articles and more particularly to aheat exchanger having integral fins.

In accordance with the teachings contained in United States Patent No.2,690,002, issued on September 28, 1954, a pattern of weld-inhibitingmaterial is applied to a weldable surface of a metal sheet over which asecond sheet is superimposed. The sheets are secured together to preventrelative movement between them and then pressure-welded together, as byrolling, in their adjacent areas not separated by the weld-inhibitingmaterial. Subsequent to the pressure welding operation, the resultantsheets are usually softened by annealing and the unjoined portiondefined by the pattern of weld-inhibiting material is outwardly expandedby injecting therein a fluid pressure of sutficient magnitude topermanently distend the sheets in the area adjacent the applied patternof weldinhibiting material. The expanded portions define a system ofpassageways for fluid flow. The aforesaid process is equally applicableto any number of superposed sheets having interposed between them anappropriate pattern of weld-inhibiting material. The resultant panelobtained by the aforesaid process is characterized by the absence of anyinterface between the complementary sheets forming the resultant panelproviding improved characteristics when used as a heat exchanger.

It is often desirable that the heat exchange tubing for boilers,refrigerators, condensers and the like be provided with external fins.Such heat transfer fins are usually brazed or soldered on the tubingexcept where the tube structure is very heavy and permits the fins to becast, extruded, or rolled. However, especially where the tubing is ofthe flat or oblong sheet metal type, thin walled tubing and the fins areusually brazed or soldered together. This is not only expensive and timeconsuming, but frequently fails to result in a rigid and efficientjoint. Generally, a brazed or soldered joint is of reduced heat exchangeefiiciency for lack of unimpeded heat transfer through the joint.Another heretofore known method of forming fins is a helical rollingmethod which, however, has the disadvantage of requiring a fully formedround tube blank together with an internal mandrel and which has thefurther disadvantage of requiring a considerably thick tube wall andcomplicated apparatus and controls for the proper extension of integralfins. This prior method is not readily adapted to formation of fins inconjunction with relatively thin sheet metal walls.

Accordingly, one object of this invention is to provide a simple, lowcost and improved design of finned heat exchangers.

Another object of this invention is to provide a novel and improvedrelatively thin and economical panel structure having integral flangesor fins suitable for various purposes such as strengthening or fasteningfor heat exchange.

Another object of this invention is to extend the surfaces of a heatexchanger fabricated according to the process of the aforesaid Frenchpatent without increasing the weight of the unit.

Other objects and advantages will .become more apparent from thefollowing drawings and description in which:

FIGURE 1 is a plan view of a sheet of metal having applied to itpatterns of weld-inhibiting material according to one embodiment of thisinvention;

FIGURE 2 is a plan view of an embodiment of this invention illustratinga system of passageways distended in accordance with the pattern ofweld-inhibiting material applied in FIGURE 1;

FIGURE 3 is a plan view illustrating a successive step in thefabrication of the finned heat exchanger from the embodiment of FIGURES1 and 2; and

FIGURE 4 illustrates one configuration of a finned heat exchanger thatmay be obtained from the panel depicted in FIGURE 3.

In accordance with this invention a pattern of Weldinhibiting materialis applied to a clean weldable surface 1 of a metal sheet 2 so as todefine a desired system of passageways 3. This pattern includes a seriesof stripes 4 interconnected at alternate adjacent terminal portions bylateral stripes 5. One of the longitudinal stripes 4, closest to alateral edge, is connected to one end of a lateral stripe 6 Whose otherend extends longitudinally to the edge of sheet 2 by means of a stripe7. Another longitudinal stripe 4, closest to the other lateral edge, isconnected to a stripe 8 which extends to an edge of sheet 2.

A plurality of additional patterns of weld-inhibiting material is alsoprovided on surface 1 of sheet 2. As illustrated in FIGURE 1 theseadditional patterns are applied in a rectangular configuration. A pairof these rectangular configurations, a long one 9 and a short one 10,are provided between each pair of adjacent longitudinal stripes 4.However, it is to be understood that a singular rectangular pattern ofweld-inhibiting material can also be used. In addition, laterallyextended rectangular patterns of weld-inhibiting material 11 and 12 areapplied adjacent each side of laterally extending stripe 6.

Subsequent to the application of the weld-inhibiting material on thesurface of sheet 2, a second sheet is superimposed on its surface 1 andpressure welded thereto in the areas not separated by weld-inhibitingmaterial in accordance :with the aforesaid United States patent. Theresultant pressure welded panel 13 is illustrated in FIGURE 2 with theunjoined portions defining the desired tubular passageways 14 expandedto facilitate the description of this invention. However, it is to beunerstood that the aforesaid passages may be either distended orundistended for fabrication of the desired structure of this invention.

Subsequent to the expansion of passages 14, the resultant unjoinedportions defined by the rectangular configurations of broken lines 19are bisected by slitting at 15, by any appropriate means such asshearing or punching or the like, in the direction lengthwise of thelongest dimension of the rectangular configuration. Two additional slits16 are provided at the terminal portions of slits 15 in a directionperpendicular thereto along the edges of the rectangular configuration19. The resultant series of slits comprise a long slit 15 terminatingperpendicularly in the mid-point of a short slit 16, forming in effect a'T-shape at each end of slit 15. In each instance, slits 15 and 16extend through both complementary portions of panel 13 adjacent therectangular unjoined area resulting from the application ofweld-inhibiting material. After the panel has been slitted, theaforesaid complementary portions are then separated from each other bybending along opposite unslitted edges of rectangle 5 so as to extend inopposite directions out of the plane of the panel to form fins orflanges 17 leaving openings 18 in the areas of-the panel from which thefins or flanges 17 were formed. it a Although a specificrectangular'configuration for t-he finned patterns and a specific meansof forming them i has been described, it is to be understood that thefin patternsinay be at any desired irregular or complex design. The finsmay also be formed .from the fin patterns by first expanding themfollowed by milling bit the crest of the expanded fin patterns.

primary 'purpose of this invention :is directed to extending theheatexchange surface of a heat exchanger by provision of fins integralwith the exchanger, it is to be understood thatuthe :resultant ;finsImay be employed And, i although the es flanges for fastening," spacersor any suitable purpose. a

Although the invention has been described with reference to specificembodiments and details, various, modifications and changes,'withintherscope of this invention,

will be apparent to one skilled in the 'art and are 'con-' temp lat'edtobe embraced within the invention;

What is claimed is: 1 g

1. A hollow article comprising a solid, seamless,'u'nitary 'met'al sheethaving within 1its" interior a first unjoined portiondefining a systemof passageways, and a second unjoined portion terminating within alledges of said 'sh'eet andhaving complementary portions of said sheetintegral with the entire sheet, adjacentzsaid said sheet.

joined portion, separated to extend in opposite'directions out-of theplane of said sheet to. form an opening through 2. A hollow articlecomprising a'solid, seamless; unitary hollow sheet having Within itsinterior a first unjoined portion defining a system of passageways for,fluid flow bulged out of :the plane of the sheet, anda second unjoinedportion terminating within'all edges of said sheet and havingcomplementary portions of said sheet, ad

jacent said second 'unjoined portion, separated to extend in oppositedirections out of the plane of said sheet to 2,375,334 *5 45 Valyi etal29-1573 2,471,960w 5/49 Johnson i 165-170 X 2,585,736 2/52 Bu-rr 165-170X -2,690;0O2-

9/54 Grenell l65 170 X CHARLES SUKALO, Primary Examiner.

second un--

1. A HOLLOW ARTICLE COMPRISING A SOLID, SEAMLESS, UNITARY METAL SHEETHAVIN WITHIN ITS INTERIOR A FIRST UNJOINED PORTION DEFINING A SYSTEM OFPASSAGEWAYS, AND A SECOND UNJOINED PORTION TERMINATING WITHIN ALL EDGESOF SAID SHEET AND HAVING COMPLEMENTARY PORTIONS OF SAID SHEET